1. Field of the Invention
This invention relates to computer keyboards, and more particularly to folding keyboards for use with very small portable computers.
2. Summary of the Background Art
An increasing use of computing devices that are significantly smaller than laptop computers, such PDAs (Personal Digital Assistants), and palmtop computers, together with the increasing ability of such devices to perform activities, such as word processing and spreadsheet operations, that have been traditionally associated with laptop and desktop computers, have led to an increasing need for suitable keyboards to use with such devices. A suitable keyboard would have keys, at least in the area of the alphabetical keys, of the standard size and configuration, together with a small overall size of the keyboard, and with an ability of the keyboard to be folded.
This need has been met by a number of designs for folding keyboards including at least some standard-sized keys. In general, these designs fall either into a first category, in which the key pattern is split into two sections, placed on opposite sides of a hinge extending across the center of the keyboard, or into a second category, in which provision is made for folding the keyboard across a conventionally staggered key pattern of the keyboard.
Examples of keyboards in this first category are described in U.S. Pat. Nos. 5,712,769, 6,168,331, U.S. Des. Pat. No. 420,655, and U.S. Des. Pat. No. 416,008. Disadvantages of such keyboards arises from the fact that the familiar pattern of a single group of staggered alphanumeric keys, as generally used for typing, cannot be provided and from the fact that the keyboard must be made larger in both its folded and open conditions to provide for spacing the two key patterns apart. Additionally, what is needed is a first latching mechanism for holding the keyboard in a folded condition, so that it can be conveniently carried without being inserted in a special carrying case, and a second latch for holding the keyboard in a fully open, or deployed condition, so that it can be readily used for typing on a soft or curved surface such as the user""s lap.
Examples of keyboards in the second category are described in U.S. Pat. Nos. 5,653,543, 6,088,220, and 6,174,097. Such keyboards must employ a solution to the problem of hinging the staggered key pattern so that the keys projecting partly past the hinge line from one side of the keyboard do not prevent the other side of the keyboard from being folded upward.
One solution to this problem is to split one or more keys at the hinge line into two parts, with one part on each side of the keyboard, and to make other keys at the hinge line smaller than their standard size, so that they each lie on only one side of the hinge line. A disadvantage of this solution, which is applied to one of the embodiments of U.S. Pat. No. 6,088,220, arises from these deviations from a standard keyboard.
Another solution to this problem is to mount a portion of each of several rows of keys within the keyboard to slide as a unit away from the hinge line before the keyboard is folded. Disadvantages of this solution arise from the complexity of mounting groups of keys to slide laterally together, and further from the fact that it is necessary to rely on the user to move these sections before the keyboard can be folded and before the keyboard can be used after being unfolded, in the method described as another embodiment of U.S. Pat. No. 6,088,220. Alternately, separate mechanisms may be employed, as described in U.S. Pat. No. 6,174,097, to provide for movement of the key segments as the keyboard is folded and unfolded. U.S. Pat. No. 6,174,097 also describes a mechanism for locking the keyboard in its unfolded condition, but this mechanism has the disadvantage of requiring a separate action of the user.
Yet another solution to this problem is to pivotally attach the two keyboard sections by means of a number of coupling links, with each coupling link including a first hole through which a rod within the first section of the keyboard extends and a second hole, spaced apart from the first hole, through which a rod from the second portion of the keyboard extends. As the second section of the keyboard is folded over the first, it is moved upward by the distance between the holes in each of the coupling links. A disadvantage of this method, as it is described in U.S. Pat. No. 5,653,543, arises from the fact that a latching means is not provided to hold the keyboard in its open, or deployed condition, so that it cannot readily be used on a curved or soft surface, such as the user""s lap.
What is needed is a simple mechanism providing for folding a keyboard having a conventionally staggered key pattern so that the keys of the opposite sections face one another with the keyboard in a folded condition, with the mechanism also locking the keyboard in a fully open condition so that it can be readily used on a curved or soft surface.
According to a first aspect of the invention, a keyboard, including a proximal section, a distal section, a sliding attachment structure, and a folding attachment structure, is provided. The proximal section includes a first plurality of keys. The distal section includes a second plurality of keys. Depression of each key in the first and second pluralities causes generation of an electrical signal. The sliding attachment structure releasably holds the proximal section together with the distal section and in alignment with the distal section. The sliding attachment structure releases the proximal section from being held in alignment with the distal section as the proximal and distal sections are pulled apart. The folding attachment structure movably attaches the proximal section and the distal section permitting the proximal section to be folded against the distal section with the sliding attachment structure releasing the proximal section from being held in alignment with the distal section.
Preferably, the first and second pluralities of keys coextend along a staggered line, being disposed upward, when the proximal and distal sections are held in alignment. When the proximal section is folded against the distal section, the first plurality of keys is disposed to face the second plurality of keys.
Preferably, the keyboard also includes a spring applying a force to the sliding attachment structure to hold the proximal and distal sections together with the sliding attachment structure. Preferably, the keyboard also includes a latch releasably holding the proximal section folded against the distal section.
Preferably, the sliding attachment structure includes a receptacle extending within the distal section and a plug extending from the proximal section to slide in the receptacle. Preferably, the folding attachment structure includes a coupling link and a slider, with the coupling link being pivotally attached to one of the sections at a first end of the coupling link, and with the slider being slidably mounted in the other of the section and being pivotally attached to the coupling link at a second end of the coupling link.